CI_COMMIT_REF_NAME have no branch name

Summary

Steps to reproduce

run pipeline on merge

What is the current bug behavior?

in variable CI_COMMIT_REF_NAME present link to branch

What is the expected correct behavior?

variable CI_COMMIT_REF_NAME mast contain branch name

Relevant logs and/or screenshots

$ env | grep -E "REF_NAME|BRANCH_NAME"

CI_COMMIT_REF_NAME=refs/merge-requests/59/head

CI_MERGE_REQUEST_SOURCE_BRANCH_NAME=test-ci

CI_BUILD_REF_NAME=refs/merge-requests/59/head

CI_MERGE_REQUEST_TARGET_BRANCH_NAME=stage

Output of checks

This bug happens on GitLab.com